Field of the Disclosure
The present disclosure relates to wireless communication systems, and more particularly to techniques for dynamic frequency selection channel scan optimizations.
Description of Related Art
Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). A wireless network, for example a Wireless Local Area Network (WLAN), such as a Wi-Fi network (IEEE 802.11) may include an access point (AP) that may communicate with at least one stations (STA) or mobile devices. The AP may be coupled to a network, such as the Internet, and enable an access terminal (AT) to communicate via the network (and/or communicate with other devices coupled to the AP).
STAs typically perform scan procedures on channels of a WLAN, e.g., passive and/or active scans. During active scans, the STA actively looks for other devices by broadcasting a probe request and then waiting to see if any devices, e.g., another STA and/or AP, sends a probe response. During passive scans, the STA listens on (or monitors) a channel to detect transmissions, e.g., beacons, probe requests/responses, packets, etc. Passive scans typically include the device listening on the channel for a maximum time period (or dwell time) that may provide for the reception of beacon transmissions from other devices, e.g., the dwell time may be selected to ensure the device is listening for a complete beacon interval. This dwell time, e.g., the time the device is monitoring the channel, may result in unnecessarily long total passive scan times. For example, when listening on the channel, the device typically performs a clear channel assessment (CCA) by detecting energy levels on the channel. If the energy levels rise above a threshold, the device determines whether or not the transmission is a radar signal and, if so, the device adds the channel to a non-occupancy list (NOL) for a time period. These long passive scan times may cause increased power use for the device. Moreover, current protocols do not provide a mechanism for the device to safely determine that a radar signal is not present, and therefore switch from a passive scan to an active scan without waiting for the maximum dwell time.